Women Can Sniff Out Men Without Knowing—And Vice Versa

Sexual chemicals affect how we identify an androgynous figure.

Women and men can sniff out the opposite sex via odorless pheromones, a new study suggests.

The discovery adds another piece to the growing body of evidence that humans, much like the rest of the animal kingdom, know more from their noses than previously thought.

"We know that for animals, chemosignals are actually the most used signals to communicate, whereas with humans, we think chemosensation is not really used," said study leader Wen Zhou, a psychologist at the Chinese Academy of Sciences in Beijing.

"But based on our experiences, they are still influenced by these cues, even if they don't explicitly know it."

In a recent experiment, subjects who smelled possible pheromones from the opposite sex were more likely to interpret ambiguous human figures as that sex—even when the participants didn't know they were smelling anything.

Pheromones—chemicals that can communicate sexual information—are widespread in the animal world, and some research suggests humans use them unconsciously as well.

Zhou and colleagues used videos of points of light moving in a way that fools the eye into seeing human motion.

The videos were made by filming real people in motion-capture suits with LEDs at each joint—similar to the suits used to create Hollywood special effects.

Then the scientists mathematically manipulated the dots until the "figures" had neither a typically male nor typically female gait.

Sex Pheromones Influence Gender Choice

Twenty men and 20 women watched the video animations of these ambiguous figures, as well as ones that were more obviously male or female. While watching the videos, the subjects sniffed clove oil infused with the male steroid androstadienone, the female steroid estratetraenol, or a plain oil used as a base for many cosmetics.

Men who smelled the female pheromone were more likely to identify the androgynous walker as a woman, and even were more likely to identify more clearly male figures as female than those who just smelled clove oil.